#include <linux/init.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/cache.h>
#include <asm/apic.h>
#include <asm/uv/uv.h>
DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
= { &init_mm, 0, };
/*
* Smarter SMP flushing macros.
* c/o Linus Torvalds.
*
* These mean you can really definitely utterly forget about
* writing to user space from interrupts. (Its not allowed anyway).
*
* Optimizations Manfred Spraul <manfred@colorfullife.com>
*
* More scalable flush, from Andi Kleen
*
* To avoid global state use 8 different call vectors.
* Each CPU uses a specific vector to trigger flushes on other
* CPUs. Depending on the received vector the target CPUs look into
* the right array slot for the flush data.
*
* With more than 8 CPUs they are hashed to the 8 available
* vectors. The limited global vector space forces us to this right now.
* In future when interrupts are split into per CPU domains this could be
* fixed, at the cost of triggering multiple IPIs in some cases.
*/
union smp_flush_state {
struct {
struct mm_struct *flush_mm;
unsigned long flush_va;
spinlock_t tlbstate_lock;
DECLARE_BITMAP(flush_cpumask, NR_CPUS);
};
char pad[INTERNODE_CACHE_BYTES];
} ____cacheline_internodealigned_in_smp;
/* State is put into the per CPU data section, but padded
to a full cache line because other CPUs can access it and we don't
want false sharing in the per cpu data segment. */
static union smp_flush_state flush_state[NUM_INVALIDATE_TLB_VECTORS];
/*
* We cannot call mmdrop() because we are in interrupt context,
* instead update mm->cpu_vm_mask.
*/
void leave_mm(int cpu)
{
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
BUG();
cpumask_clear_cpu(cpu,
mm_cpumask(percpu_read(cpu_tlbstate.active_mm)));
load_cr3(swapper_pg_dir);
}
EXPORT_SYMBOL_GPL(leave_mm);
/*
*
* The flush IPI assumes that a thread switch happens in this order:
* [cpu0: the cpu that switches]
* 1) switch_mm() either 1a) or 1b)
* 1a) thread switch to a different mm
* 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask);
* Stop ipi delivery for the old mm. This is not synchronized with
* the other cpus, but smp_invalidate_interrupt ignore flush ipis
* for the wrong mm, and in the worst case we perform a superfluous
* tlb flush.
* 1a2) set cpu mmu_state to TLBSTATE_OK
* Now the smp_invalidate_interrupt won't call leave_mm if cpu0
* was in lazy tlb mode.
* 1a3) update cpu active_mm
* Now cpu0 accepts tlb flushes for the new mm.
* 1a4) cpu_set(cpu, new_mm->cpu_vm_mask);
* Now the other cpus will send tlb flush ipis.
* 1a4) change cr3.
* 1b) thread switch without mm change
* cpu active_mm is correct, cpu0 already handles
* flush ipis.
* 1b1) set cpu mmu_state to TLBSTATE_OK
* 1b2) test_and_set the cpu bit in cpu_vm_mask.
* Atomically set the bit [other cpus will start sending flush ipis],
* and test the bit.
* 1b3) if the bit was 0: leave_mm was called, flush the tlb.
* 2) switch %%esp, ie current
*
* The interrupt must handle 2 special cases:
* - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm.
* - the cpu performs speculative tlb reads, i.e. even if the cpu only
* runs in kernel space, the cpu could load tlb entries for user space
* pages.
*
* The good news is that cpu mmu_state is local to each cpu, no
* write/read ordering problems.
*/
/*
* TLB flush IPI:
*
* 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
* 2) Leave the mm if we are in the lazy tlb mode.
*
* Interrupts are disabled.
*/
/*
* FIXME: use of asmlinkage is not consistent. On x86_64 it's noop
* but still used for documentation purpose but the usage is slightly
* inconsistent. On x86_32, asmlinkage is regparm(0) but interrupt
* entry calls in with the first parameter in %eax. Maybe define
* intrlinkage?
*/
#ifdef CONFIG_X86_64
asmlinkage
#endif
void smp_invalidate_interrupt(struct pt_regs *regs)
{
unsigned int cpu;
unsigned int sender;
union smp_flush_state *f;
cpu = smp_processor_id();
/*
* orig_rax contains the negated interrupt vector.
* Use that to determine where the sender put the data.
*/
sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
f = &flush_state[sender];
if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
goto out;
/*
* This was a BUG() but until someone can quote me the
* line from the intel manual that guarantees an IPI to
* multiple CPUs is retried _only_ on the erroring CPUs
* its staying as a return
*
* BUG();
*/
if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
if (f->flush_va == TLB_FLUSH_ALL)
local_flush_tlb();
else
__flush_tlb_one(f->flush_va);
} else
leave_mm(cpu);
}
out:
ack_APIC_irq();
smp_mb__before_clear_bit();
cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
smp_mb__after_clear_bit();
inc_irq_stat(irq_tlb_count);
}
static void flush_tlb_others_ipi(const struct cpumask *cpumask,
struct mm_struct *mm, unsigned long va)
{
unsigned int sender;
union smp_flush_state *f;
/* Caller has disabled preemption */
sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS;
f = &flush_state[sender];
/*
* Could avoid this lock when
* num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is
* probably not worth checking this for a cache-hot lock.
*/
spin_lock(&f->tlbstate_lock);
f->flush_mm = mm;
f->flush_va = va;
if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) {
/*
* We have to send the IPI only to
* CPUs affected.
*/
apic->send_IPI_mask(to_cpumask(f->flush_cpumask),
INVALIDATE_TLB_VECTOR_START + sender);
while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
cpu_relax();
}
f->flush_mm = NULL;
f->flush_va = 0;
spin_unlock(&f->tlbstate_lock);
}
void native_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm, unsigned long va)
{
if (is_uv_system()) {
unsigned int cpu;
cpu = get_cpu();
cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
if (cpumask)
flush_tlb_others_ipi(cpumask, mm, va);
put_cpu();
return;
}
flush_tlb_others_ipi(cpumask, mm, va);
}
static int __cpuinit init_smp_flush(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(flush_state); i++)
spin_lock_init(&flush_state[i].tlbstate_lock);
return 0;
}
core_initcall(init_smp_flush);
void flush_tlb_current_task(void)
{
struct mm_struct *mm = current->mm;
preempt_disable();
local_flush_tlb();
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
preempt_enable();
}
void flush_tlb_mm(struct mm_struct *mm)
{
preempt_disable();
if (current->active_mm == mm) {
if (current->mm)
local_flush_tlb();
else
leave_mm(smp_processor_id());
}
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
preempt_enable();
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
{
struct mm_struct *mm = vma->vm_mm;
preempt_disable();
if (current->active_mm == mm) {
if (current->mm)
__flush_tlb_one(va);
else
leave_mm(smp_processor_id());
}
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, va);
preempt_enable();
}
static void do_flush_tlb_all(void *info)
{
unsigned long cpu = smp_processor_id();
__flush_tlb_all();
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_LAZY)
leave_mm(cpu);
}
void flush_tlb_all(void)
{
on_each_cpu(do_flush_tlb_all, NULL, 1);
}
